Car4-positive adipocyte progenitor cells adapt to the aging environment and work as protection against ROS via glutathione metabolism.

The induction of beige adipocytes is significantly reduced in aged mice due to the senescence of adipocyte progenitor cells (APCs). Recent studies have revealed the existence of beige adipocyte subtypes, suggesting that APCs comprise a heterogeneous population. Therefore, in this study, we aimed to elucidate the mechanism through which long-term cold exposure induces the production of beige adipocytes even in aged mice. Single-cell RNA sequencing identified carbonic anhydrase 4 (Car4)-positive APCs. The number of Car4-positive APCs increased with age and cold exposure. Car4 knockdown (KD) mitigated intracellular pH reduction and significantly suppressed beige adipocyte differentiation. Furthermore, Car4 KD cells demonstrated reduced expression of genes in the glutathione pathway and increased susceptibility to reactive oxygen species (ROS), which was alleviated by glutathione supplementation. Our findings suggest that ROS resistance is an adaptation to the cellular aging environment. Our study provides insights into the age-related decline in beige adipocyte induction and identifies Car4 as a potential therapeutic target for enhancing energy expenditure in elderly individuals. This may pave the way for the development of new strategies to combat age-related metabolic diseases and offer hope for improved health and longevity in an aging population.